| 1. |
- Jiang, Richard M., et al.
(författare)
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Accelerated regression-based summary statistics for discrete stochastic systems via approximate simulators
- 2021
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Ingår i: BMC Bioinformatics. - : BioMed Central (BMC). - 1471-2105. ; 22
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Tidskriftsartikel (refereegranskat)abstract
- Background: Approximate Bayesian Computation (ABC) has become a key tool for calibrating the parameters of discrete stochastic biochemical models. For higher dimensional models and data, its performance is strongly dependent on having a representative set of summary statistics. While regression-based methods have been demonstrated to allow for the automatic construction of effective summary statistics, their reliance on first simulating a large training set creates a significant overhead when applying these methods to discrete stochastic models for which simulation is relatively expensive. In this tau work, we present a method to reduce this computational burden by leveraging approximate simulators of these systems, such as ordinary differential equations and tau-Leaping approximations.Results: We have developed an algorithm to accelerate the construction of regression-based summary statistics for Approximate Bayesian Computation by selectively using the faster approximate algorithms for simulations. By posing the problem as one of ratio estimation, we use state-of-the-art methods in machine learning to show that, in many cases, our algorithm can significantly reduce the number of simulations from the full resolution model at a minimal cost to accuracy and little additional tuning from the user. We demonstrate the usefulness and robustness of our method with four different experiments.Conclusions: We provide a novel algorithm for accelerating the construction of summary statistics for stochastic biochemical systems. Compared to the standard practice of exclusively training from exact simulator samples, our method is able to dramatically reduce the number of required calls to the stochastic simulator at a minimal loss in accuracy. This can immediately be implemented to increase the overall speed of the ABC workflow for estimating parameters in complex systems.
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| 2. |
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| 3. |
- Feng, Yi, et al.
(författare)
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Design of a Printable Multi-Functional Sensor for Remote Monitoring
- 2011
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Ingår i: 2011 IEEE SENSORS Proceedings. - : IEEE Sensors Council. - 9781424492893 ; , s. 675-678
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a novel printable multi-functional passive sensor for remote monitoring. The sensor mainly consists of a series of pairs of transmission lines and sensing resistors whose resistances vary with one physical parameter. A short-duration radio-frequency pulse as interrogation signal travels along the transmission line and is partially reflected at each resistor due to impedance mismatch. By measuring the energies of the discrete reflected pulses in time domain, all the physical parameters could be detected simultaneously. This design not only saves complex circuitry but also enables easy adaptation for detecting multiple parameters. We have theoretically analyzed the sensor assuming it has an arbitrary number of sensing resistors. The introduced algorithm between the pulse energies and resistances is verified by simulation. As a prototype, an inkjet-printed sensor on polyimide foil is presented. The experimental measurement has successfully proven the design concept.
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| 4. |
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| 5. |
- Feng, Yifan, et al.
(författare)
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Fractal Superconducting Nanowire Single-Photon Detectors and Their Applications in Imaging
- 2022
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Ingår i: 2022 Conference on Lasers and Electro-Optics Pacific Rim, CLEO-PR 2022 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc..
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Konferensbidrag (refereegranskat)abstract
- We present our research on fractal superconducting nanowire single-photon detectors and their applications in light detection and ranging (LiDAR), full-Stokes polarimetric imaging, and non-line-of-sight imaging.
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| 6. |
- Feng, Yi, et al.
(författare)
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Low Cost Printed Chipless RFID Humidity Sensor Tag for Intelligent Packaging
- 2015
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Ingår i: IEEE Sensors Journal. - 1530-437X .- 1558-1748. ; 15:6, s. 3201-3208
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a fully-printed chipless radio frequency identification sensor tag for short-range item identification and humidity monitoring applications. The tag consists of two planar inductor-capacitor resonators operating wirelessly through inductive coupling. One resonator is used to encode ID data based on frequency spectrum signature, and another one works as a humidity sensor, utilizing a paper substrate as a sensing material. The sensing performances of three paper substrates, including commercial packaging paper, are investigated. The use of paper provides excellent sensitivity and reasonable response time to humidity. The cheap and robust packaging paper, particularly, exhibits the largest sensitivity over the relative humidity range from 20% to 70%, which offers the possibility of directly printing the sensor tag on traditional packages to make the package intelligent at ultralow cost.
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| 7. |
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| 8. |
- Forné, Anna, 1971
(författare)
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“Una suma de negaciones”: Apuntes sobre el género testimonial y el Premio Casa de las Américas (1970-1976)
- 2015
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Ingår i: Kamchatka. Revista de análisis cultural.. - 2340-1869. ; :6, s. 251-267
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Tidskriftsartikel (refereegranskat)abstract
- En este artículo se examinan los años de institucionalización del género testimonio por medio de un análisis de dos de las obras premiadas por Casa de las Américas en su premio literario anual en la categoría ‘testimonio’ entre 1970-1976. El objetivo es abordar la conceptualización estético-política del género testimonio establecida e institucionalizada por medio del premio y asimismo ver cómo se articulan las relaciones entre poética y política en las obras mismas. Partiendo de la hipótesis que las modalidades y el grado de intervención discursiva del escritor-editor condiciona la literariedad de esta categoría de relatos, el análisis en particular abordará la presencia autorial con el fin de aproximarse a las relaciones entre estética y política en el género testimonial.
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| 9. |
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| 10. |
- Gu, Jian, et al.
(författare)
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TGF-beta-Induced CD4(+) Foxp3(+) T Cells Attenuate Acute Graft-versus-Host Disease by Suppressing Expansion and Killing of Effector CD8(+) Cells
- 2014
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 193:7, s. 3388-3397
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Tidskriftsartikel (refereegranskat)abstract
- The use of TGF-beta-induced CD4(+) Foxp3(+) T cells (induced regulatory T cells [iTregs]) is an important prevention and treatment strategy in autoimmune diseases and other disorders. However, the potential use of iTregs as a treatment modality for acute graft-versus-host disease (aGVHD) has not been realized because they may be unstable and less suppressive in this disease. We restudied the ability of iTregs to prevent and treat aGVHD in two mouse models. Our results showed that, as long as an appropriate iTreg-generation protocol is used, these iTregs consistently displayed a potent ability to control aGVHD development and reduce mortality in the aGVHD animal models. iTreg infusion markedly suppressed the engraftment of donor CD8(+) cells and CD4(+) cells, the expression of granzyme A and B, the cytotoxic effect of donor CD8(+) cells, and the production of T cell cytokines in aGVHD. Therefore, we conclude that as long as the correct methods for generating iTregs are used, they can prevent and even treat aGVHD.
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| 11. |
- Lin, M., et al.
(författare)
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Control of a manufacturing cell using a generic layered architecture
- 1999
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Ingår i: Proceedings of the 1st Workshop on Robot Motion and Control, RoMoCo 1999. - 0780356551 - 9780780356559 ; , s. 107-112
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Konferensbidrag (refereegranskat)abstract
- This paper describes an implementation of a control system for an experimental two-robot manufacturing cell. The implementation is based on a generic layered software architecture which supports both periodic and event-driven computations. The use of the layered software architecture as the framework for designing and implementing hybrid controllers contributes to the ease of system development and is therefore strongly advocated. In order to illustrate the approach some of the implementation details are also presented.
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| 12. |
- Lin, Man, et al.
(författare)
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Quantitative ventilation assessments of idealized urban canopy layers with various urban layouts and the same building packing density
- 2014
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Ingår i: Building and Environment. - : Elsevier BV. - 0360-1323 .- 1873-684X. ; 79, s. 152-167
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Tidskriftsartikel (refereegranskat)abstract
- This paper investigates urban canopy layers (UCLs) ventilation under neutral atmospheric condition with the same building area density (Ap = 0.25) and frontal area density ()V = 0.25) but various urban sizes, building height variations, overall urban forms and wind directions. Turbulent airflows are first predicted by CFD simulations with standard k-e model evaluated by wind tunnel data. Then air change rates per hour (ACH) and canopy purging flow rate (PFR) are numerically analyzed to quantify the rate of air exchange and the net ventilation capacity induced by mean flows and turbulence. With a parallel approaching wind (0 = 0), the velocity ratio first decreases in the adjustment region, followed by the fully-developed region where the flow reaches a balance. Although the flow quantities macroscopically keep constant, however ACH decreases and overall UCL ventilation becomes worse if urban size rises from 390 m to 5 km. Theoretically if urban size is infinite, ACH may reach a minimum value depending on local roof ventilation, and it rises from 1.7 to 7.5 if the standard deviation of building height variations increases (0%-833%). Overall UCL ventilation capacity (PFR) with a square overall urban form (Lx = Ly = 390 m) is better as 0 = 0 than oblique winds (0 = 15, 30, 45), and it exceeds that of a staggered urban form under all wind directions (0 = 0 -45), but is less than that of a rectangular urban form (Lx = 570 m, Ly -= 270 m) under most wind directions (0 = 30 -90). Further investigations are still required to quantify the net ventilation efficiency induced by mean flows and turbulence.
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| 13. |
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| 14. |
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| 15. |
- Liu, Yuwei, et al.
(författare)
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The effects of fermented rye products on gut microbiota and their association with metabolic factors in Chinese adults : an explorative study
- 2021
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Ingår i: Food & Function. - : Royal Society of Chemistry. - 2042-6496 .- 2042-650X. ; 12:19, s. 9141-9150
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Tidskriftsartikel (refereegranskat)abstract
- Rye is among the cereals with the highest content of dietary fibre. A high rye food intake has been associated with improved metabolic risk factors in some but not all observational and intervention studies. Whole-grain rye has also been suggested to affect the gut microbiota in individuals with metabolic syndrome. However, it is yet unclear to what extent effects on the gut microbiota mediate the beneficial metabolic responses of whole-grain rye intake. We hypothesized that a high intake of whole grain rye products containing fermented rye bran (FRB) vs. refined wheat based products (RW) could alter the gut microbiota and short-chain fatty acid (SCFA) composition towards a phenotype associated with beneficial metabolic effects in a population not used to such foods. For this purpose, we conducted a post hoc analysis of a 12-week randomized controlled trial in Chinese adults with Helicobacter pylori (HP) infection, with 53 participants consuming RW and 31 participants consuming FRB included in the analysis. Anthropometric measurements and fasting blood and fecal sample analyses as well as 13C-urea breath test were performed at baseline and after a 12-week intervention. At week 12, we observed a higher serum insulin concentration (P-value = 0.038) in the FRB group (n = 31) versus the RW group (n = 53), and this difference was corroborated with alterations in the genus-level relative abundances of the gut microbiota, represented by an increase in Romboutsia and a reduction in Bilophila in the FRB group (n = 22) versus the RW group (n = 46). Compared to the RW group (n = 53), fecal acetic acid concentration was significantly higher in the FRB group (n = 31) at week 12. We also found that fecal acetic and butyric acids positively, while isobutyric, isovaleric and 2-methylbutyric acids inversely, correlated with the gut Romboutsia level among all participants (n = 68) at week 12. We found positive correlations of fecal isobutyric, isovaleric and 2-methylbutyric acids with gut Bilophila (n = 68). In conclusion, our results suggest that the intake of high-fibre rye products could modify gut Romboutsia and Bilophila in a Chinese population with HP infection. These effects are paralleled with favorable modifications of the SCFA concentration and are associated with altered glycemic traits.
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| 16. |
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| 17. |
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| 18. |
- Liu, Yuanhua, 1971, et al.
(författare)
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Usability Evaluation of a GUI Prototype for a Ventilator Machine.
- 2005
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Ingår i: International Journal of Clinical Monitoring and Computing. - : Springer Science and Business Media LLC. - 0167-9945 .- 1387-1307 .- 1573-2614. ; 18:5-6, s. 365-372
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Tidskriftsartikel (refereegranskat)abstract
- Objective. Information presentation on the monitor screen of ventilator machines affects nurses' response and decision-making during ventilation treatment. The purpose of this study is to evaluate whether a new GUI (graphical user interface) prototype, the so-called circular displayprototype can make deviations easy to detect. Method. A numerical display prototype was made and used as a reference displ ay in the evaluation. Six task scenarios that involved parameter changes were selected to simulate a real situation under volume control (VC) mode during ventilation treatment. Usability tests with the two display designs were carried out in a usability laboratory. Twenty medical nursing students participated as test subjects in the usability tests. Results. The objective results showed that the graphical circular display had an advantage over the numerical display in interpreting parameter changes, but not in reducing the error rates for detecting the number of parameter changes or for forming an overall picture of the patient's situation. Furthermore, the circular display prototype did not improve the detection time. Conclusions. Although the majority of the test subjects preferred the graphical circular display, the results implied that several aspects of this prototype should be improved in a future development study.
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| 19. |
- Liu, Zhuofan, et al.
(författare)
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Comparison of a time- and a speed-based traffic light assistance system
- 2018
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Ingår i: Cognition, Technology & Work. - : Springer London. - 1435-5558 .- 1435-5566. ; 20, s. 93-103
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Tidskriftsartikel (refereegranskat)abstract
- Traffic light assistance systems (TLASs) can be infrastructure based or on-board, and in the latter case they can inform the driver about the time remaining to green, or about the recommended speed for a smooth passage at green. A speed-based and a time-based on-board system prototype was compared against each other and against a baseline without any assistance system. Using a within-subjects design, 18 participants drove in a fixed-base simulator along a suburban road with signalised intersections, where the delay to green was set to zero (allowing a passage at the current speed), “half-speed” (requiring a clear speed reduction) and “stop” (requiring a substantial speed reduction). Driving behaviour, visual attention distribution and acceptance were evaluated. Both support systems improved driving efficiency and comfort over baseline, with the time-based system achieving higher scores in general. Both systems attracted a substantial amount of visual attention in the current setting; however, single-glance durations were below 1 s, and the number of glances forward were equal in the time-based condition compared to baseline, but lower in the speed-based condition. No red or amber light violations were registered in baseline, while some occurred with any of the systems. Acceptance for both systems was high, with higher scores for the time-based prototype. Overall, an on-board TLAS with a countdown timer to green has the potential to increase efficiency and comfort without strong indications for attention disruption, but the risk for increased red/amber light violations has to be addressed. Improved system design as a way to mitigate potential issues is discussed.
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| 20. |
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| 21. |
- Liu, Zhenjiang
(författare)
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MHC class I restricted and antigen-specific TCRs against viral and tumor-associated antigens (TAAs) for future biological therapy
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Adoptive cellular immunotherapy (ACT) refers to the process of transferring immune cells (autologous or allogeneic) directly to the host as a treatment for cancer or infectious diseases. The effector cells could be antigen-specific, like T cells, or non-specific, such as NK cells or lymphokine-activated killer (LAK) cells. A substantial amount of evidence shows that T cells play an important role in controlling pathogens and tumor growth. Controlling pathogens and orchestrating the function of immune cells depends on engagement of the nominal TCR (T- cell receptor) with its ligand (the MHC class I or -II peptide complex), the structure and function of T cell receptor (TCR) and the subsequent immune effector functions upon TCR triggering (cytotoxicity, proliferation, cytokine production). Tumor-infiltrating T-cells (TILs) represent a source of T-cells for the immunotherapy of patients with tumors of the central nervous system and pancreas. According to the results of paper I and II, we successfully established a rapid TIL expansion protocol for patients with brain tumors or pancreatic cancer. TILs were shown to produce Th1-cytokines and were able to recognize autologous tumor cells defined by cytokine production or cytoxicity. In paper III, we found that tumor associated antigens (TAAs)-reactive T-cells could be successfully expanded from patients with glioma with IL-2, IL-15 and IL-21; they exhibit a Th1 cytokine pattern and a central memory phenotype. NY-ESO-1 expression was found in 15/38 cases and survivin expression in 20/40 cases in glioblastoma, defined by immunohisto- chemistry. Thus, NY-ESO-1 or survivin represent a potential target for anti-NY-ESO-1 or anti-survivin directed T-cells for the biological therapy of patients with glioblastoma (GBM). Mesothelin was first identified to be overexpressed in ovarian cancer. It is constitutively expressed in normal tissue, e.g. pericardium, pleura or peritoneum. This 40kDa protein could serve as a tumor marker and as a target of immunotherapy for anti-cancer directed T-cells. In paper IV, mesothelin was found to be expressed in 4 out of 11 GBM tissues, by immune- fluorescence staining. Mesothelin directed T cell reactions were also observed in a whole blood assay (WBA) measured in 293 patients with brain tumors. Mesothelin immunogenic epitopes were also identified using a peptide mapping assay; mesothelin-specific TILs could be expanded from glioma samples. We analyzed in detail potential prospective factors in patients with GBM (n=145) and non- GBM (n=60) which refers to glioma (WHO grade II or III). In paper V, we performed univariate Kaplan-Meier (K-M) survival analysis by setting of groups based on demographic, clinical, immunological parameters and immunological reactivity patterns, then we defined factor(s) with a cut-off strategy. We performed further multivariate analysis with a Cox proportional hazards model (forward and backward stepwise analysis) to determine the key factor related with patient’s survival by considering (and omitting) interactions between employed factors. We found that T-cell reactivity to an individual survivin epitope (97-111) is positively related (P=0.024) with survival of patients with GBM. The same was found to be true for the serum cytokine pattern of IL-4/IL-5/IL-6 (P=0.052) and IFN-γ/TNF-α/IL-17A (P=0.003) which could serve as ‘predictor’ for prognosis in clinical settings. The cytokine serum profile as well as the immune reactivity to survivin may serve as a clinically relevant indicator for the clinical follow up of patients with GBM after surgery and provide a viable option to offer tailored immunological therapy.
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| 22. |
- Qian, Zhao, et al.
(författare)
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Energetic and structural analysis of N2H4BH3 inorganic solid and its modified material for hydrogen storage
- 2013
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Ingår i: International journal of hydrogen energy. - : Elsevier. - 0360-3199 .- 1879-3487. ; 38:16, s. 6718-6725
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Tidskriftsartikel (refereegranskat)abstract
- Here we have exposed the electronic structure, chemical bonding of the light-weight N2H4BH3 inorganic material for hydrogen storage applications and analyzed its hydrogen removal energetics using state-of-the-art first-principles method. The mechanism for the H-host bond weakening in this kind of solid has also been explored. It is shown that the electronic density of states of N(2)H(4)BH(3)d solid near the Fermi level is mainly contributed by the B p-states, H (B) s-states, and the end N p-states. The calculated smallest hydrogen removal energy of N2H4BH3 solid is 4.16 eV. One Li-modified structure has been obtained through ab initio relaxations and its hydrogen removal energies are found dramatically decreased by as much as 50% compared with those of pristine N2H4BH3 solid. The B-H bond weakening is attributed to the elongation of the bond length; for the N H bonds, the weakening is found to be due to the destabilization of N-H bonds before hydrogen removal and the stabilization of residual N-H bond after hydrogen removal. The weakening of these bonds is of great significance for the improvement of hydrogen desorption kinetics of the material. We propose this study should help to deepen understanding of properties of N2H4BH3 inorganic solid and its related materials for hydrogen storage applications and guide experimentalists and engineers to develop better candidate materials for the advance of the field.
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| 23. |
- Rachlew (Källne), Elisabeth, 1944-
(författare)
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Ultrashort-Lived Non-Rydberg Doubly Excited Resonances Observed in Molecular Photoionization
- 1996
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Ingår i: Physical Review Letters. - : American Institute of Physics (AIP). - 0031-9007 .- 1079-7114. ; 76, s. 4136-4139
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Tidskriftsartikel (refereegranskat)abstract
- The N2 1sB 2 Xd dispersed fluorescence from photon excited N2 molecules has been measured in the 19–34 eV excitation range, where our theory predicts the existence of non-Rydberg doubly excited resonances which autoionize in the sub-fs regime into the N2 1 B2S1u ionic state. The experimentally deduced vibrational branching ratios sy0 1dysy0 0d revealed five prominent features, four of which could be identified as such doubly excited resonances based on the lowest order of the many-body perturbation theory. [S0031-9007(96)00230-X]
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| 24. |
- Sabella, D., et al.
(författare)
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Energy management in mobile networks towards 5G
- 2016
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Ingår i: Studies in Systems, Decision and Control. - Cham : Springer International Publishing. ; , s. 397-427
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Konferensbidrag (refereegranskat)abstract
- The evolution of mobile networks from the introduction of the first generation systems until today, and the forecasts for the next decade [1], clearly indicate a growth of both the network itself in terms of installed equipment and carried traffic in terms of transmitted bits. The deployment of new generation systems upon existing ones unavoidably increases the energy consumption, even if new systems are more efficient than the older ones. More consumption means more costs, i.e., less margins for the operators, and greater carbon footprint from the entire Planet. On the other hand, for operators, it would not be possible to dismiss old generation systems in lieu of the new ones, due to the presence of legacy terminals in the network. For these reasons operators need to perform accurate assessment of the energy performance of 2G, 3G and 4G networks by looking in perspective at the evolution of the network in terms of traffic growth, change of paradigms/business models, introduction of next generation networks (i.e. 5G) and so on. This book chapter focuses on the energy efficiency aspects relevant for a sustainable evolution of mobile networks towards 5G from an operator perspective. The conducted analysis will cover both network deployment aspects, equipment evolution, introduction of energy efficiency features, cost analysis, network-level energy efficiency assessment and related standardization initiatives.
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| 25. |
- Sabelnikov, Vladimir, 1946, et al.
(författare)
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A balance equation for the mean rate of product creation in premixed turbulent flames
- 2017
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Ingår i: Proceedings of the Combustion Institute. - : Elsevier BV. - 1540-7489. ; 36:2, s. 1893-1901
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Tidskriftsartikel (refereegranskat)abstract
- Transport equations for reaction rate W and its Favre-averaged value W̃ are derived from first principle in the case of premixed turbulent combustion. The assumptions made for derivation hold for unity Lewis number premixed flames at least in the flamelet regime of turbulent burning. Analysis of the latter equation shows that it involves two dominant terms, but the difference between them vanishes if reaction zones retain the structure of the zone in the unperturbed laminar flame. However, in such a case, turbulent burning velocity cannot grow with time during interaction of an initially laminar flame with a turbulent flow. Therefore, the analysis indicates a vital role played by local perturbations of reaction zone structure in premixed turbulent combustion. The dominance of these two terms and the important role played by the difference between them are confirmed by analyzing three DNS databases associated with both the corrugated flamelets and thin reaction zones regimes of premixed turbulent burning. Moreover, the DNS data show that perturbations of local displacement speed due to perturbations of local flamelet structure are also of paramount importance for modeling transport of flame surface density even in weakly turbulent flows. Finally, by simulating curved and/or strained laminar premixed flames and integrating the transport equation for W across the flames, the integral is shown to depend linearly on the stretch rate even in highly perturbed flames, with results obtained from variously stretched flames being close to each other. Based on this finding, the difference between the two dominant terms in the transport equation for the mean rate W̃ is hypothesized to depend linearly on the stretch rate conditioned to the reaction zone. Application of this hypothesis to the DNS data associated with the corrugated flamelets combustion regime yields encouraging results, thus, confirming a crucial role played by local perturbations of reaction zone structure even in weakly turbulent flames.
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| 26. |
- Shi, Juanzi
(författare)
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Nanoscale organization of luminescent materials and their polarization properties investigated by two-dimensional polarization imaging
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Semiconductor materials (e.g., conjugated polymers, metal halide perovskites) have been widely used in solar cells, light-emitting diodes, and photodetectors. Organic conjugated systems have high mechanical flexibility and low costs for production. Metal halide perovskites have the advantage of strong light absorption, long charge-carrier diffusion lengths, and low intrinsic surface recombination.Polarization-sensitive single-molecule methods have been extensively used to study the chromophore organization and excitation energy transfer (EET) process. Our novel polarization technique, two-dimensional polarization imaging (2D POLIM) is designed to simultaneously measure and control both the excitation and emission polarization characteristics of an individual object. A model based on single funnel approximation (SFA) is applied to fit the 2D polarization portrait obtained from 2D POLIM measurements. 2D POLIM in combination with the SFA model allows the quantitative characterization of EET efficiency. Overall, A large number of polarization parameters, e.g., modulation depths, phases, luminescence shift, fluorescence anisotropy, energy funneling efficiency, and properties of the EET-emitter, can be extracted from 2D polarization portraits. They give a full picture of chromophores’ organization and a quantitative measure of the EET process.In this thesis, we applied the 2D POLIM technique to investigate the fundamental optoelectronic process in different types of luminescent materials. H-aggregates forming in spin-cast conjugated films are visualized by modulation depth and phase imaging contrast. Light-harvesting efficiency shows the efficient ET within the amorphous phase and poor ET between H-aggregates due to the less overlap between absorption and emission spectra. Together with single-molecule spectroscopy and scanning electron microscope, we studied the polarization property of individual MAPbBr3 aggregates, which shows the well-known dielectric screening effect cannot fully explain the absorption polarization from weakly elongated objects (even with irregular shapes). We propose that power dependent quantum yield can further increase the modulation depth of excitation. 2D POLIM was also applied to explore the aggregation state of proteins in the biological system. Furthermore, we did a series of computer experiments to examine and improve the SFA model. We break the limit of energy funneling efficiency and propose an asymmetric three-dipole model, which is more applicable for multi-chromophore systems. In the future, quantitative phase-contrast imaging and time-resolved 2D POLIM might be further developed
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| 27. |
- Wang, Q., et al.
(författare)
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Improved practical decoy state method in quantum key distribution with parametric down-conversion source
- 2007
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Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 79:4
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a new decoy state scheme for quantum key distribution with parametric down-conversion source is proposed. We use both three-intensity decoy states and their triggered and nontriggered components to estimate the fraction of single-photon counts and the quantum bit-error rate of single-photon pulses, and then deduce a more accurate value of the key generation rate. The final key rate over transmission distance is simulated, which shows that we can obtain a higher key rate than that of the existing methods, including our own earlier work.
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| 28. |
- Wang, Y. T., et al.
(författare)
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Regional gastrointestinal transit and pH studied in 215 healthy volunteers using the wireless motility capsule : influence of age, gender, study country and testing protocol
- 2015
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Ingår i: Alimentary Pharmacology and Therapeutics. - : Wiley. - 0269-2813 .- 1365-2036. ; 42:6, s. 761-772
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundThe wireless motility capsule (WMC) offers the ability to investigate luminal gastrointestinal (GI) physiology in a minimally invasive manner. AimTo investigate the effect of testing protocol, gender, age and study country on regional GI transit times and associated pH values using the WMC. MethodsRegional GI transit times and pH values were determined in 215 healthy volunteers from USA and Sweden studied using the WMC over a 6.5-year period. The effects of test protocol, gender, age and study country were examined. ResultsFor GI transit times, testing protocol was associated with differences in gastric emptying time (GET; shorter with protocol 2 (motility capsule ingested immediately after meal) vs. protocol 1 (motility capsule immediately before): median difference: 52min, P=0.0063) and colonic transit time (CTT; longer with protocol 2: median 140min, P=0.0189), but had no overall effect on whole gut transit time. Females had longer GET (by median 17min, P=0.0307), and also longer CTT by (104min, P=0.0285) and whole gut transit time by (263min, P=0.0077). Increasing age was associated with shorter small bowel transit time (P=0.002), and study country also influenced small bowel and CTTs. Whole gut and CTTs showed clustering of data at values separated by 24h, suggesting that describing these measures as continuous variables is invalid. Testing protocol, gender and study country also significantly influenced pH values. ConclusionsRegional GI transit times and pH values, delineated using the wireless motility capsule (WMC), vary based on testing protocol, gender, age and country. Standardisation of testing is crucial for cross-referencing in clinical practice and future research.
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| 29. |
- Xu, Shijie
(författare)
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Large eddy simulation of dual-fuel combustion under ICE conditions
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present thesis aims at studying n-heptane/methanol dual-fuel combustion under internal combustion engine conditions and strives to improve the understanding of its ignition, combustion, and pollutant emission mechanisms. Large-eddy simulation (LES) coupled with Eulerian stochastic fields (ESF) approach is employed to simulate single/dual-fuel combustion in a constant-volume vessel to mimic the single/dual-fuel combustion in conventional/dual-fuel premixed engines. The experimental configuration from Engine Combustion Network (ECN) is considered as the baseline case in the simulations. The main works are summarized in two parts: model development and studies of the fundamental physics involved in dual-fuel combustion.First, the ESF approach with a novel modified method is proposed, implemented, and evaluated. Results show that the modified ESF method removes the numerical error in the element mass conservation and shows capability in predicting both premixed and non-premixed flames relevant to dual-fuel combustion. Second, LES of n-heptane single-fuel and n-heptane/methanol dual-fuel combustion is carried out and validated against ECN Spray-H experiments. A good agreement is obtained in terms of flow, combustion, and emissions characteristics. Finally, a parameter study is performed to investigate the effects of the dual-fuel strategies, including the primary fuel concentration, the ambient temperature, and the pilot fuel injection timing. It is concluded that: 1) The ambient methanol is found to have an effect of suppressing the two-stage ignition and heat release of n-heptane, this is more significant under high ambient methanol concentration conditions. 2) The effects of methanol on the n-heptane ignition and NOx formation are strongly dependent on the ambient temperatures. The retardation of the n-heptane high temperature ignition is more remarkable under low ambient temperatures. The NOx and soot in the dual-fuel case is lower than that of the single-fuel case in moderately high initial temperatures, while an opposite trend is observed in higher temperatures. 3) A late injection may lead to an overlap of the ambient methanol auto-ignition and the delivery of n-heptane. This overlap results in high soot and NOx formation.
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| 30. |
- Xu, Shijie, et al.
(författare)
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Large-eddy simulation of the injection timing effects on the dual-fuel spray flame
- 2022
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 310
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Tidskriftsartikel (refereegranskat)abstract
- Large-eddy simulations (LES) coupled with a partially-stirred reactor model and a finite-rate chemistry are carried out to investigate the effects of n-heptane injection timing on the methanol fueled dual-fuel (DF) combustion. Methanol is premixed with air in a constant volume chamber (T=1000 K, ρ=14.8 kg/m3) to form a homogeneous mixture (equivalence ratio ϕm of 0.3). Liquid fuel n-heptane is provided from a high pressure injector to mimic the pilot fuel injection in DF engines. First, mesh sensitivity analysis and LES model validation are conducted. The experimental data of Spray-H (n-heptane fueled) from the Engine Combustion Network is used for model validation. It is shown that the present mesh and LES model are capable of replicating the liquid and vapor penetration length, mixture fraction, temperature distribution, pressure rise profile and ignition delay time (IDT). Second, the effects of n-heptane injection timing are investigated, by varying the start of injection (SOI) time. The LES results reveal that there are three stage heat releases in the DF combustion. With the delay of SOI, the mass fraction of hydrogen peroxide in the ambient mixture increases, leading to an early formation of hydroxyl. Therefore, the two-stage IDTs of n-heptane decrease, while the ambient methanol IDT increases. Results also show the cool flame and high-temperature flame evolution after methanol auto-ignition. The cool flame disappears while the high-temperature flame is found near the injector nozzle, which leads to a relatively high heat release rate.
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| 31. |
- Yu Rud, V., et al.
(författare)
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Toward new opportunities in the study of the biological potential of plants
- 2022
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Ingår i: IOP Conference Series: Earth and Environmental Science, Volume 1096. - : Institute of Physics (IOP).
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Konferensbidrag (refereegranskat)abstract
- This work is devoted to the discussion of the peculiarities of studying the optical and photovoltaic properties of plants in order to increase the effectiveness of the study of the biological potential of plants and their protection. In the article we try to analyze the validity of our conclusions, citing proven experimental methods of solid state physics for studying plants. These studies were conducted on a wide range of plants. The analysis of the obtained results allows us to conclude that the main the result obtained in the studies of photoelectrical properties with the application of the methods developed and improved by us can actually serve to control the condition of the plant, acting as a kind of markers in the study of their biological potential. © Published under licence by IOP Publishing Ltd.
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| 32. |
- Zhu, Yanlei, et al.
(författare)
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Deciphering the Unexpected Binding Capacity of the Third PDZ Domain of Whirlin to Various Cochlear Hair Cell Partners
- 2020
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Ingår i: Journal of Molecular Biology. - : Elsevier BV. - 0022-2836 .- 1089-8638. ; 432:22, s. 5920-5937
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Tidskriftsartikel (refereegranskat)abstract
- Hearing is a mechanical and neurochemical process, which occurs in the hair cells of inner ear that converts the sound vibrations into electrical signals transmitted to the brain. The multi-PDZ scaffolding protein whirlin plays a critical role in the formation and function of stereocilia exposed at the surface of hair cells. In this article, we reported seven stereociliary proteins that encode PDZ binding motifs (PBM) and interact with whirlin PDZ3, where four of them are first reported. We solved the atomic resolution structures of complexes between whirlin PDZ3 and the PBMs of myosin 15a, CASK, harmonin a1 and taperin. Interestingly, the PBM of CASK and taperin are rare non-canonical PBM, which are not localized at the extreme C terminus. This large capacity to accommodate various partners could be related to the distinct functions of whirlin at different stages of the hair cell development. (C) 2020 Published by Elsevier Ltd.
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